Ragwort (Jacobaea vulgaris)

Common Ragwort is a wildflower found throughout the UK, recognised for its clusters of bright golden-yellow flowers and deeply divided dark green leaves. Ragwort is toxic if ingested by humans and livestock, so it should be handled with care and kept away from grazing animals. Flowering from late spring and through the summer, the flower heads can be gathered for natural dyeing before they set seed, taking care to wear gloves when handling the plant due to its toxic properties.

Ragwort flowers contain natural yellow pigments that produce vibrant dye colours. When simmered they typically yield bright golden yellows to rich mustard shades, depending on the quantity of flowers used and the length of the dyeing process.

Ragwort contains only low levels of natural tannins, so the colours benefit from the use of mordants. Alum generally produces bright yellow shades, while iron deepens the colour to olive, khaki, or muted greenish-brown tones.

Ragwort dyes work particularly well on wool and silk, producing strong, lightfast yellows, while cotton and linen usually develop softer, paler shades. As the flowers grow abundantly in meadows, roadside verges, and unmanaged grassland, ragwort has long been valued as a traditional natural dye plant. However, because it is poisonous, any leftover plant material and dye bath should be disposed of responsibly, and utensils used for dyeing should not be used for food preparation.

Top image shows tests using silk, cotton, linen and wool samples.
Samples were tested with no mordant, alum mordant and iron mordants as well as using a soda ash modifier after dyeing